Wardle discovered that attackers could bypass the signature check by naming their malware file a certain way. And once they’re in, they could get root access and control the victim’s Mac. The Verge says Wardle disclosed the bug to Zoom back in December 2021, but the fix it rolled out contained another bug. This second vulnerability could have given attackers a way to circumvent the safeguard Zoom set in place to make sure an update delivers the latest version of the app. Wardle reportedly found that it’s possible to trick a tool that facilitates Zoom’s update distribution into accepting an older version of the video conferencing software.
Zoom already fixed that flaw, as well, but Wardle found yet another vulnerability, which he has also presented at the conference. He discovered that there’s a point in time between the auto-installer’s verification of a software package and the actual installation process that allows an attacker to inject malicious code into the update. A downloaded package meant for installation can apparently retain its original read-write permissions allowing any user to modify it. That means even users without root access could swap its contents with malicious code and gain control of the target computer.
The company told The Verge that it’s now working on a patch for the new vulnerability Wardle has disclosed. As Wired notes, though, attackers need to have existing access to a user’s device to be able to exploit these flaws. Even if there’s no immediate danger for most people, Zoom advises users to “keep up to date with the latest version” of the app whenever one comes out.
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